C-flow stacked plate heat exchanger

ABSTRACT

A primary surface plate-type heat exchanger has sheets with triangular zones on opposite sides of a central rectangular area stacked alternately to provide a C-shaped flow path for two fluids. Corrugations in the sheet surface serve to direct fluid flow and to support adjacent sheets.

United States Patent [191 Dawson et al.

[ Sept. 18, 1973 1 1 C-FLOW STACKED PLATE HEAT EXCHANGER [75] inventors:Harry J. Dawson, Dunlap; Wallace A. Hottiezer, Peoria; David E. Keedy,Pekin; Ervin E. Mangus, Brimfield; Eugene K. Patton; Joseph P.Grandlleld, both of Peoria, all of I11.

{73] Assignee: Caterpillar Tractor Co., Peoria, 111.

[22] Filed: Nov. 18, 1971 211 App]. No.: 199,928

[52] US. Cl. 165/166 [51] Int. Cl. F28b 3/04 [58] Field of Search165/166, 167

[56] References Cited UNITED STATES PATENTS 8/1970 Rothman 165/1663,183,963 5/1965 Mondt 165/166 X 3,249,155 5/1966 Huet 165/166 3,256,9306/1966 Norback 165/166 3,364,992 1/1968 Biabaud 165/166 3,613,78210/1971 Mason 165/166 Primary Examiner-Charles J. Myhre AssistantExaminer-Theophil W. Streuhler, Jr.

Attorney-Donald C. Feix et a1.

57 ABSTRACT A primary surface plate-type heat exchanger has sheets withtriangular zones on opposite sides of a central rectangular area stackedalternately to provide a C- shaped flow path for two fluids.Corrugations in the sheet surface serve to direct fluid flow and tosupport adjacent sheets.

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4 Sheets-Sheet 2 a W A 3114 92 MR INVENTORS HARRY J. DAWSON WALLACE A.HOFTIEZER DAVID E. KEEDY ERVIN E. MANGUS EUGENE K,PATTON JOSEPH P.GRANDFIELD ATTORNEYS Patented Sept. 18, 1973 4 SheetsSheet 5 A GA\? 52 m54 G S HARRY J. DAWSON WALLACE A. HOFTlEZER DAVID E. KEEDY ERVIN E.MANGUS EUGENE K. PATTON JOSEPH P. GRANDFIELD ATTORNEYS 'Patentecl Sept.18, 1973 INVFNTURS HARRY J. DAWSON WALLACE A. HOFTIEZER DAVID E. KEEDYERVIN E. NGUS EUGENE K. PATTON JOSEPH F? ANDFIELD 1 C-FLOW STACKED PLATEHEAT EXCHANGER BACKGROUND OF THE INVENTION 2,321,110 issued June 8, 19433,042,382 issued July 3, 1962 3,216,494 issued Nov. 9, 1965 3,29l,206issued Dec. 13, 1966 None of the prior art constructions, such as thoseindicated above, has heretofore presented a compact, relativelyadaptable construction that could be mated with an internal combustionengine with a minimum of complex and expensive ducting.

SUMMARY OF THE INVENTION It is an object of this invention to provide acompact, low profile, primary surface heat exchanger.

Another object is to arrange an efficient primary surface heat exchangerso that the respective flow paths of fluids through the exchanger aregenerally C-shaped.

Another object is a heat exchanger compatible with typical enginearrangements to reduce costly ducting requirements and consequently toreduce flow dynamic losses attributed to ducting.

Other objects and advantages of the present invention will become morereadily apparent upon reference to the accompanying drawings andfollowing description.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is an exploded perspective view of a group of plates;

FIG. 2 is a sectional view taken in the direction of arrows II--II inFIG. 1 and FIG.

FIG. 3 is a sectional view taken in the direction of arrows III-III inFIG. 1 and FIG. 6;

FIG. 4 is a sectional view taken in the direction of arrows IV-IV inFIG. 1;

FIGS. 5 and 6 are plan views of an alternate arrangement of plates;

FIG. 7 is a sectional view taken in the direction of arrows VII-VII inFIG. 5;

FIG. 8 is a partial plan view showing the stacked relationship ofadjacent sheets detailed in FIGS. 5 and 6;

FIG. 9 is a sectional view taken in the direction of arrows IX-IX inFIG. 8;

FIG. 10 is a perspective view of an alternative form of two adjacentplates;

FIG. 11 is a perspective view of a typical gas turbine engine showingone application of the subject invention; and

FIG. 12 is a schematic diagram illustrating fluid flow paths through theheat exchanger arrangement presented in FIG. 11.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, four Sheets 2, 4, 6and 8 are shown, with Sheet 2 identical to Sheet 6, and Sheet 4identical to Sheet 8.

Each sheet contains three principal regions. For example, Sheet 2 has acorrugated central rectangular area 10 flanked by embossedtriangular-shaped zones 12 and 14 on both sides.

In the triangular zone 12, a base 16 is coincident with one side of thecentral rectangular area 10, so that the sides 18 and 20 therefore formtwo of the six outer edges of Sheet 2.

Edge bars, such as 22 and 24 attached to Sheet 2, 26 and 28 attached toSheet 4, and 30 and 32 attached to Sheet 6, serve to space the sheetsapart as well as seal the edges, thus preventing leakage and intermixingof fluids.

One edge of each triangular shaped zone, such as 34 and 36 on Sheet 8,and 110 and 112 on Sheet 6, is not sealed by an edge bar, therebyforming apertures when Sheets 4, 6 and 8 are stacked.

While only four sheets are shown in FIG. 1, it should be understood thata large number of sheets are stacked in pairs, such as Sheets 2 and 4,to form a heat exchanger core of the desired size.

Typical sections of the Sheets 2 and 4 are shown in FIGS. 2 and 3,respectively.

As may readily be seen, when the Sheet 2 is placed on the Sheet 4 toform one pair of plates in a stack, the sheets will be supported andspaced apart by the edge bars 26 and 28 and by the crowns 38 and thevalleys 40 of corrugations in the central rectangular area of thesheets.

Likewise, dimples or thimbles embossed into the sheets in the triangularside zones provide support and spacing for these areas of the sheets.

In FIG. 4, it can be seen that the embossments 42 terminate short of theouter edge 44, thus providing a narrow flat margin 46 for the attachmentof edge bars such as the bar 32.

This forms an effective seal to prevent leakage and intermixing offluids.

An alternate arrangement, wherein the central rectangular area isflanked by two triangular shaped zones on each side, is presented inFIGS. 5 and 6.

In FIG. 5, the edge bars 48, 50, 52, 54, 56 and 58 are attached to theSheet 60.

In FIG. 6, the edge bars 62 and 64 are attached to the Sheet 66.

The Sheets and 66 are flat throughout the triangu lar side zones.

As shown in section in FIG. 7, filler Sheets 68 are placed in the zoneto provide structural support and directional guidance of flow. Theseplates may be placed loosely on the Sheet 60, or attached to the edgebar 54 other so that corrugations on adjacent sheets will contact,thereby providing structural support and preventing nesting of thesheets.

A typical application of this invention is FIG. 11.

A heat exchanger or recuperator 84 formed by successively stacking thesheets 60 and 66, detailed in FIGS. 5 and 6, is shown installed on a gasturbine engine 86.

The ducts 88 and 88' connect on a compressor discharge collector 90 to arecuperator 84, while the duct 92 connects the recuperator 841 to acombustor collector 94.

A recuperator housing 96, with openings for ducts 88, 88', and 92, isplaced on an exhaust collector 98.

Although partially hidden in FIG. 11, the total recuperator system shownconsists of two heat exchanger units, shown generally at 100 and 100' inschematic fashion in FIG. 12.

Identical elements in the two units are identified by like referencenumbers, but set apart by a prime designation.

illustrated in OPERATION While the operation of the present invention isbelieved clearly apparent from the foregoing description, furtheramplification will subsequently be made in the following brief summaryof such operation.

A typical application for this invention is on a gas turbine enginewherein heat energy available in the exhaust gas is recovered by theheat exchanger assembly and is transferred to combustion inlet air. Itis the application that will be used to demonstrate the operation ofthis invention.

For continuity, the flow path of relatively hot engine exhaust gas willbe indicated on the drawings by solid line arrows.

Similarly, the convention of representing the relatively coolercompressor discharge air by phantom line arrows will be adopted.

The advantages to be gained, such as operating economy and increasedefficiency, by employing a stacked plate heat exchanger with an internalcombustion engine, are well known.

The generally C-shaped paths described by the air flow can easily beseen in FIG. 1. For instance, air flow 102 between the sheets 2 and 4 isdirected by the locations of the entrance opening 104 and exit opening106 provided between the two sheets.

The edge bars 26 and 28 effectively seal all edges around the peripheryof the sheets except for the aforementioned flow entry and exitapertures 102 and 104.

Similarly, a somewhat shallower C-shaped flow path 108 is provided forgas flow, as indicated between the sheets 4 and 6.

The edge bars 30 and 32 effectively seal the appropriate edges as shown,thus creating the entrance opening 110 and the exit opening 112.

As can be seen, the location of the apertures encourages a natural, andhighly desirable, counterdirectional flow path for the respective fluidsacross the central rectangular zone.

The corrugations in the central rectangular zone provide not onlystructural support, as previously mentioned, but also aid in flowcontrol.

The chevron pattern illustrated in FIG. 1, sectioned in FIGS. 2 and 3,and shown in stacked position in FIG.

8, encourages mixing of the fluid flow during its travel across thezone, thus preventing buildup of a laminar flow condition which would bedetrimental to efficient heat transfer.

Likewise, the wavy corrugation pattern, illustrated in FIGS. 5 and 6,has characteristics similar to the chevron pattern.

Another alternative, the skewed straight passage, is shown in FIG. 10.As a result of crossing of crowns and valleys of corrugations inadjacent sheets, all three pat terns provide structural support,directional flow control, and mixing of the flow within the respectivepassage to encourage efficient heat transfer with minimum pressure loss.

Also, since the subject primary surface heat exchanger does not dependupon finned surfaces for the bulk of its heat transfer, the relativelythin patterned sheets outlined above may be fabricated from metal,ceramic, or other nonmetallic material without affecting overallperformance. For example, materials such as silicon nitride, siliconcarbide, and lithium-aluminasilicate currently being evaluated by theindustry for high temperature applications, may be used to form thesheets of the heat exchanger disclosed herein.

The two outside edges of the triangular side zones may be varied inlength, with respect to each other, to accommodate specific flow densityand duct work requirements. Normally, the edge corresponding tocompressor discharge air flow will be shorter than the adjacent legcorresponding to exhaust gas flow due to the greater density of thecompressed, cooler compressor discharge air.

The particular flow path of fluid through a typical engine is presentedin FIGS. 11 and 12.

Compressor discharge air is directed to the collector and subsequentlyrouted by the ducts 88 and 88' to the inlet apertures 114, 114', 116,and 116' of the heat exchangers 84 and 84'.

The air then passes in generally C-shaped flow paths through the centralrectangular areas receiving heat energy in the'known manner by transferthrough the cor rugated sheets from hot exhaust gas.

The air, thus heated, is conducted from the discharge ports (orapertures) 118, 118, 120 and 120 of exchangers 84 and 84 to thecombustor collectors by the ducts 92 and 92'.

The air then proceeds on through the engine in the conventional manneri.e., being heated further by the introduction of fuel into the air,subsequent ignition of the fuel thus forming a hot gas which in turnpasses over one or more turbine rotors or stages transforming heatenergy in the gas into mechanical energy in a rotating member, thendischarging into the exhaust collector 98.

The relatively hot exhaust gas then passes into the recuperator housing96 and 96', passing through the heat exchanger 84 and 84, giving up heatenergy to the cooler combustor inlet air by transfer through the platesof said exchanger, and finally passing out of the housing into theatmosphere.

In view of the foregoing, it is readily apparent that the structure ofthe present invention provides a compact, low profile, primary surfaceheat exchanger, compatible with typical engine arrangements, so that therespective fluid flow path of fluids through the exchanger describes ageneral C-shape.

While the invention has been described and shown with particularreference to the preferred embodiments, it is apparent that variationsmight be possible that would fall within the scope of the presentinvention which is not intended to be limited, except as defined in thefollowing claims We claim:

1. A primary surface heat exchanger comprising first and second sheetsalternately arranged to form a stack, said sheets each having acorrugated central rectangular area with opposite sides and ends, andtriangularshaped areas having first and second edges and a basecoincident with each of said rectangular area sides, portions ofadjacent sheets abutting to provide structural support for said sheetsand to maintain generally uniform flow paths between the sheets, saidfirst and second edges of said triangular-shaped areas forming acuteangles with the adjacent side of the rectangular area, side sheetsdefining therebetween a first C-shaped fluid flow path entering andexiting between said first edges of the triangular-shaped areas fortravel across said rectangular area from side to side, and a secondC-shaped fluid flow path immediately adjacent said first flow path inthe stack and entering and exiting between said second edges for travelacross said rectangular area from side to side in substantiallycounter-flow relation to said first flow path.

2. The invention of claim 1 including seal means attached to said firstand second sheets to seal appropriate edges of said sheets and to formnoncommunicating fluid passages and to provide structural support forsaid 6 stack.

3. The invention of claim 1 wherein said central rectangular areafurther comprises corrugations which are chevron-shaped and have crownsand valleys arranged in ranks and aligned so that crowns of saidcorrugations in said first sheets contact valleys of said corrugationsof said second sheets, thus providing structural support for saidsheets.

4. The invention of claim I wherein said central rectangular areafurther comprises corrugations which are wave-shaped and have crowns andvalleys arranged in ranks and aligned so thatcrowns of said corrugationsin said first sheets contact valleys of said corrugations of said secondsheets, thus providing structural support for said sheets.

5. The invention of claim 1 wherein said central rectangular areafurther comprises straight corrugations which are arranged in ranks andaligned so that said corrugations of said first sheet are skewed inrelation ship to said corrugations of said second sheet.

6. The invention of claim I wherein said triangularshaped areas havedimples embossed thereon to provide structural support for said sheets.

7. The invention of claim 1 further comprising at least twotriangular-shaped corrugated sheets coincident with thetriangular-shaped areas, thus providing structural support for saidsheets.

8. The invention of claim 1 wherein the corrugated sheets are made ofnonmetallic material.

1. A primary surface heat exchanger comprising first and second sheetsalternately arranged to form a stack, said sheets each having acorrugated central rectangular area with opposite sides and ends, andtriangular-shaped areas having first and second edges and a basecoincident with each of said rectangular area sides, portions ofadjacent sheets abutting to provide structural support for said sheetsand to maintain generally uniform flow paths between the sheets, saidfirst and second edges of said triangular-shaped areas forming acuteangles with the adjacent side of the rectangular area, side sheetsdefining therebetween a first C-shaped fluid flow path entering andexiting between said first edges of the triangular-shaped areas fortravel across said rectangular area from side to side, and a secondC-shaped fluid flow path immediately adjacent said first flow path inthe stack and entering and exiting between said second edges for travelacross said rectangular area from side to side in substantiallycounter-flow relation to said first flow path.
 2. The invention of claim1 including seal means attached to said first and second sheets to sealappropriate edges of said sheets and to form noncommunicating fluidpassages and to provide structural support for said stack.
 3. Theinvention of claim 1 wherein said central rectangular area furthercomprises corrugations which are chevron-shaped and have crowns andvalleys arranged in ranks and aligned so that crowns of saidcorrugations in said first sheets contact valleys of said corrugationsof said second sheets, thus providing structural support for saidsheets.
 4. The invention of claim 1 wherein said central rectangulararea further comprises corrugations which are wave-shaped and havecrowns and valleys arranged in ranks and aligned so that crowns of saidcorrugations in said first sheets contact valleys of said corrugationsof said second sheets, thus providing structural support for saidsheets.
 5. The invention of claim 1 wherein said central rectangulararea further comprises straight corrugations which are arranged in ranksand aligned so that said corrugations of said first sheet are skewed inrelationship to said corrugations of said second sheet.
 6. The inventionof claim 1 wherein said triangular-shaped areas have dimples embossedthereon to provide structural support for said sheets.
 7. The inventionof claim 1 further comprising At least two triangular-shaped corrugatedsheets coincident with the triangular-shaped areas, thus providingstructural support for said sheets.
 8. The invention of claim 1 whereinthe corrugated sheets are made of nonmetallic material.